1. Field of the Invention
The present invention relates to a liquid encapsulated bushing used, for example, in a section for supporting a suspension arm of an automobile on a vehicle body.
2. Description of the Related Art
A liquid encapsulated bushing is known, for example, as described in Japanese Patent Application Laid-open No. 1-275209. In such a liquid encapsulated bushing, the dynamic spring constant can be reduced compared to the prior art bushing in which the absorption of a vibration is performed only by the elasticity of a bushing rubber. Hence, the load noise can be effectively decreased.
In the known liquid encapsulated bushing described in Japanese Patent Application Laid-open No. 1-275209, an inner tube and an outer tube are connected to each other by a single bushing rubber. For this reason, it is difficult not only to finely regulate axial and radial spring characteristics of the bushing rubber, but also to establish any sectional shape of a liquid chamber defined in the bushing rubber.
In addition, the known liquid encapsulated bushing described in Japanese Patent Application Laid-open No. 1-275209 includes a liquid chamber in an area where a cylindrical bushing rubber, which interconnects the inner and outer tubes, is in contact with the inner tube. For this reason, it is necessary not only to define an injecting bore, which extends through the outer tube and the bushing rubber, for injecting a liquid into the liquid chamber, but also to occlude the injecting bore after injection of the liquid. Thus, it is difficult to produce the liquid encapsulated bushing, and the cost is increased.